Backward Causation/Multiple You

Can a future event have impact on past events? This is the good question of the day:

For every choice you make, there’s the choice you didn’t make, and both realities are real and valid, and both exist “out there.” That means there’s infinite versions of yourself. I can grasp the basic concept of this, but I don’t have any answers as to how the timeline branches, how having multiple you’s on multiple timelines affects your soul, and why we can have all these different timelines / us’ existing independently of each other, with each one of them believing they are the only version of themselves and reality out there, completely oblivious to their other selves….

That fork you chose, what if you went another way, the impact of potentiality within the multiverse dictates that parallel you’s inhabit those little bubble universes being born and dying each moment.

Is the dream world a place to experience this, and why have the great mystics and teachers planted in time always insist upon laying down the sword?